The invention relates to a linear guide device, and particularly to a linear guide device that is suitably employed in, for example, a semiconductor producing apparatus in which usual grease or a lubricating oil cannot be used.
Conventionally, a linear guide device having the following configuration is known (for example, Japanese Patent Publication (Kokai) No. HEI5-248433). The linear guide device has a linear guide rail and a movable unit which is moved along the guide rail. The movable unit is configured by: a movable block in which leg portions are arranged in a lateral direction with respect to the moving direction, and which is disposed with straddling the guide rail; and plural rolling elements which, while circulating in rolling element circulation passages formed in the right and left leg portions of the movable block, roll between a rolling element raceway surface formed in the circulation passage, and other rolling element raceway surfaces respectively formed on both the sides of the guide rail.
In a linear guide device of such a type, usually, grease is used for lubrication between the rolling elements, and the guide rail and the movable block. The device is used in a state where the clearance between the guide rail and the movable unit and in a direction perpendicular to the moving direction is formed as a negative clearance, or a preload is applied between the movable block and the guide rail via the rolling elements.
When such a linear guide device is employed in an environment where high cleanness or oil free is required, such as in a semiconductor producing apparatus, usual grease or a lubricating oil cannot be used, and hence at least rolling element contact surfaces (raceway surfaces) of the guide rail and the movable block must be coated with a solid lubricating agent.
When a solid lubricating agent is used in a linear guide device, the life (dust evolution and torque life) of the device is more easily affected by a load as compared with the case where grease is used. As described above, a linear guide device of this type is used with being applied with a preload and forming a negative clearance. Therefore, the device is always in a state where a relatively large load is acting on the device, thereby producing a problem in that the device has a short life.